1. Field of the Invention
The present invention relates to a vibrating gyroscope used as, for example, a position detecting sensor.
2. Description of the Related Art
FIG. 7 is a top view schematically illustrating an example of a conventional vibrating gyroscope, disclosed in the Unexamined Japanese Patent Application Publication No. 10-300475. A vibrating gyroscope 1 is formed of a substrate 30, a vibrating sensor device 31, a signal processing circuit 32, a first driving wiring pattern 33a, a second driving wiring pattern 33b, a first detecting wiring pattern 34a, a second detecting wiring pattern 34b, a compensation wiring pattern 35, and wiring patterns (36a, 36b, 36c, and 36d).
The vibrating sensor device 31 and the signal processing circuit 32 are disposed in the same plane of the substrate 30, and are connected to each other by the first and second driving wiring patterns 33a and 33b, the first and second detecting wiring patterns 34a and 34b, and the wiring patterns 36.
The vibrating sensor device 31 is configured, such as that shown in FIG. 4. The vibrating sensor device 31 shown in FIG. 4 has a device substrate 3, on which a supporting stationary portion 4, comb-like driving stationary electrodes 5 (5a, 5b, 5c, 5d, 5e, 5f, 5g, and 5h), and detecting stationary electrodes 6 (6a, 6b, 6c, 6d, 6e, and 6f) are disposed. A vibrator 8 is connected to the supporting stationary portion 4 via support portions (7a and 7b).
The vibrator 8 is disposed away from the device substrate 3, and is formed of driving beams 9 (9a, 9b, 9c, and 9d), an outer frame 10, comb-like driving movable electrodes 11 (11a, 11b, 11c, 11d, 11e, 11f, 11g, and 11h), support portions 12a and 12b, detecting beams 13 (13a, 13b, 13c, and 13d), an inner frame 14, and comb-like detecting movable electrodes 15 (15a, 15b, 15c, 15d, and 15f).
One end of each of the driving beams 9a and 9b is connected to the support portion 7a, and one end of each of the driving beams 9c and 9d is connected to the support portion 7b. The other ends of the driving beams 9a, 9b, 9c, and 9d are connected to the outer frame 10.
The outer frame 10 can vibrate in the X direction shown in FIG. 4. This is discussed in detail below. In the outer frame 10, the comb-like driving movable electrodes 11 are meshed with the corresponding comb-like driving stationary electrodes 5 such that they are away from each other with a predetermined space. The comb-like driving stationary electrodes 5a, 5b, 5c, and 5d and the comb-like driving movable electrodes 11a, 11b, 11c, and 11d form a first driving unit. The comb-like driving stationary electrodes 5e, 5f, 5g, and 5h and the comb-like driving movable electrodes 11e, 11f, 11g, and 11h form a second driving unit.
The first driving unit is electrically connected to the first driving wiring pattern 33a or the second driving wiring pattern 33b (for example, the first driving wiring pattern 33a) shown in FIG. 7 via an electrode pad (not shown) or wiring (not shown). The second driving unit is electrically connected to the first driving wiring pattern 33a or the second driving wiring pattern 33b (for example, the second driving wiring pattern 33b) via an electrode pad (not shown) or wiring (not shown).
The support portions 12a and 12b extend inward away from the outer frame 10. The detecting beams 13a and 13b extend from the forward-facing end of the support portion 12a, while the detecting beams 13c and 13d extend from the forward-facing end of the support portion 12b. 
The inner frame 14 is connected to the forward-facing ends of the detecting beams 13a, 13b, 13c, and 13d. The inner frame 14 can vibrate integrally with the outer frame 10 in the X direction. The inner frame 14 can also vibrate in the Y direction relative to the outer frame 10. The vibration of the inner frame 14 is discussed below. In the inner frame 14, the comb-like detecting movable electrodes 15 are meshed with the corresponding comb-like detecting stationary electrodes 6 such that they are away from each other with a predetermined space. The comb-like detecting stationary electrodes 6a, 6b, and 6c and the comb-like detecting movable electrodes 15a, 15b, and 15c form a first detecting unit. The comb-like detecting stationary electrodes 6d, 6e, and 6f and the comb-like detecting movable electrodes 15d, 15e, and 15f form a second detecting unit.
The first detecting unit is electrically connected to the first detecting wiring pattern 34a or the second detecting wiring pattern 34b (for example, the first detecting wiring pattern 34a) shown in FIG. 7 via an electrode pad (not shown) or wiring (not shown). The second detecting unit is electrically connected to the first detecting wiring pattern 34a or the second detecting wiring pattern 34b (for example, the second detecting wiring pattern 34b) via an electrode pad (not shown) or wiring (not shown).
In the vibrating sensor device 31 constructed as described above and as shown in FIG. 4, a first driving signal and a second driving signal, which are 180 degrees out of phase with each other, are applied to both the first driving unit and the second driving unit, which are formed by the driving stationary electrodes 5 and the driving movable electrodes 11, via the first driving wiring pattern 33a and the second driving wiring pattern 33b, respectively. Then, the magnitude of the capacitance is changed on the basis of the driving signals so that the overall vibrator 8 vibrates in the X direction shown in FIG. 4 by utilizing the rust elasticity of the driving beams 9 while being supported by the support portions 7a and 7b. 
By rotating the overall vibrator 8 in the Z direction (perpendicular to the plane of FIG. 4) while it is vibrating in the X direction, a Coriolis force is generated orthogonal to the driving direction (X direction) of the vibrator 8 and the central-axis direction (Z direction) of the rotation of the vibrator 8, that is, in the Y direction. Because of this Coriolis force, the inner frame 14 of the vibrator 8 vibrates in the Y direction relative to the outer frame 10 by utilizing the elasticity of the detecting beams 13 while being supported by the support portions 12a and 12b. 
By detecting a change in the capacitance between the detecting stationary electrodes 6 and the detecting movable electrodes 15 based on the vibration of the inner frame 14 in the Y direction, the magnitude of the angular velocity around the Z axis can be determined.
To avoid adverse influences, such as air damping, the above-configured vibrator 8 is generally housed and sealed in a space formed between, for example, a lid member, and the device substrate 3 while being decompressed. In this case, the driving stationary electrodes 5 and the detecting stationary electrodes 6 of the vibrating sensor device 31 are electrically connected to exterior components via through-holes provided in the lid member.
FIG. 5 illustrates an example of the signal processing circuit 32 to be connected to the vibrating sensor device 31. In FIG. 5, the essential portions of the vibrating sensor device 31 are also shown. The signal processing circuit 32 is formed of a first detecting C-V converter 21, a second detecting C-V converter 22, a first first-stage amplifying circuit 23a, a second first-stage amplifying circuit 23b, a summing amplifier 24, a differential amplifier 25, an auto gain control (AGC) unit 26, and a phase inverter 27. For simple representation of the signal processing circuit 32, the driving stationary electrodes 5, the detecting stationary electrodes 6, the vibrator 8, the driving movable electrodes 11, and the detecting movable electrodes 15 of the vibrating sensor device 31 are shown in a simplified form in FIG. 5.
The first detecting C-V converter 21 is connected to the first detecting unit of the vibrator sensor device 31 via, for example, the first detecting wiring pattern 34a. The first detecting C-V converter 21 then converts the total capacitance between the detecting stationary electrodes (6a, 6b, and 6c) and the detecting movable electrodes 15 (15a, 15b, and 15c) into a voltage, and outputs the resulting signal. The second detecting C-V converter 22 is connected to the second detecting unit of the vibrator sensor device 31 via, for example, the second detecting wiring pattern 34b. The second detecting C-V converter 22 then converts the total capacitance between the detecting stationary electrodes 6 (6d, 6e, and 6f) and the detecting movable electrodes 15 (15d, 15e, and 15f) into a voltage, and outputs the resulting signal.
It is now assumed that the vibrator 8 vibrates only in the X direction. In this case, the signal output from the first detecting C-V converter 21 has a waveform indicated by the one-dot-chain line A1 shown in (a) of FIG. 6. The signal output from the second detecting C-V converter 22 has a waveform indicated by the one-dot chain line A2 shown in (b) of FIG. 6. The signal A1 has the same amplitude as and is in phase with the signal A2. The signals A1 and A2 are 90 degrees out of phase with the above-described first and second driving signals for driving the vibrator 8.
It is now assumed that the inner frame 14 of the vibrator 8 vibrates not only in the X direction, but also in the Y direction (Coriolis force direction) because of a Coriolis force generated by the angular velocity about the Z axis shown in FIG. 4. In this case, the first detecting C-V converter 21 outputs a superimposed signal of the signal component A1 and a signal component B1 generated by the angular velocity (Coriolis force) and indicated by the solid line B1 shown in (a) of FIG. 6. The amplitude of the signal component B1 is determined by the magnitude of the angular velocity, and the signal component B is 90 degrees out of phase with the signal component A1.
The second detecting C-V converter 22 outputs a superimposed signal of the signal component A2 and a signal component B2 generated by a Coriolis force and indicated by the solid line B2 shown in (b) of FIG. 6. The amplitude of the signal component B2 is determined by the magnitude of the angular velocity, and the signal component B2 is 90 degrees out of phase with the signal component A2. In other words, the amplitude of the signal component B2 is substantially the same amplitude as that of the signal component B1. The signal component B2 is 180 degrees out of phase with the signal component B1.
As discussed above, the first and second detecting C-V converters 21 and 22 output the signals according to the vibration state of the vibrator 8 to the summing amplifier 24 and the differential amplifier 25 via the first and second first-stage amplifying circuits 23a and 23b. 
The summing amplifier 24 sums the signals output from the first and second detecting C-V converters 21 and 22, and amplifies the resulting signal. As a result of the summing performed by the summing amplifier 24, the signal component B1 output from the first detecting C-V converter 21 and the signal component B2 output from the second detecting C-V converter 22 cancel each other, and are thus eliminated. Accordingly, only the addition signal of the signal components A1 and A2, i.e., the signal generated by only the vibration of the vibrator 8, is output from the summing amplifier 24 to the AGC unit 26 as a driving detection signal (monitor signal).
The AGC unit 26 outputs a driving signal based on the above-described driving detection signal by performing positive feedback control so that the vibrator 8 can stably vibrate at a resonant frequency in a preset driving direction. The driving signal is directly applied to (i) the first driving unit formed by the driving stationary electrodes 5 (5a, 5b, 5c, and 5d ) and the driving movable electrodes 11 (11a, 11b, 11c, and 11d), or (ii) the second driving unit formed by the driving stationary electrodes 5 (5e, 5f, 5g, and 5h and the driving movable electrodes 11 (11e, 11f, 11g, and 11h) (to the second driving unit in the example shown in FIG. 5) as a second driving signal via the second driving wiring pattern 33b. Then, a signal obtained by inverting the phase of the above-mentioned second driving signal by using the phase inverter 27 is applied to the other driving unit (in this case, the first driving unit) as a first driving signal via the first driving wiring pattern 33a. The vibrator 8 vibrates as described above because of the application of the first and second driving signals. That is, based on the vibration state of the vibrator 8 in the driving direction (X direction) detected as described above, positive feedback control is performed on the first and second driving units, thereby stabilizing the vibration of the vibrator 8 in the driving direction.
The differential amplifier 25 amplifies a difference between the signal output from the first detecting C-V converter 21 and the signal from the second detecting C-V converter 22. As a result of the differential amplification performed by the differential amplifier 25, the signal component A1 output from the first detecting C-V converter 21 and the signal component A2 from the second detecting C-V converter 22 cancel each other, and are thus eliminated. Accordingly, the differential amplifier 25 outputs an addition signal of the signal components B1 and B2 as an angular velocity signal. The magnitude of the angular velocity around the Z axis can be detected on the basis of the angular velocity signal.
The wiring patterns 33a, 33b, 34a, and 34b for connecting the vibrating sensor device 31 to the signal processing circuit 32 are arranged side by side, as shown in FIG. 7. Thus, due to capacitances C1, C2, and C3 generated between the corresponding adjacent wiring patterns, noise components caused by the first and second driving signals respectively transmitted in the driving wiring patterns 33a and 33b are superimposed on the detection signals transmitted in the first and second detecting wirings patterns 34a and 34b. 
As stated above, however, the first driving signal transmitted in the first driving wiring pattern 33a is 180 degrees out of phase with the second driving signal transmitted in the second driving wiring pattern 33b. Thus, by disposing the first driving wiring pattern 33a, the first detecting wiring pattern 34a, and the second driving wiring pattern 33b so that the capacitance C1 becomes substantially equal to the capacitance C2, the noise components caused by the first driving signal and the noise components by the second driving signal cancel each other in the detection signal transmitted in the first detecting wiring pattern 34a which is interposed between the first driving wiring pattern 33a and the second driving wiring pattern 33b. Thus, the detection signal contains very little noise caused by the driving signals.
In contrast, the second detecting wiring pattern 34b is greatly influenced by only the second driving signal transmitted in the second driving wiring pattern 33b. Accordingly, the noise components caused by the second driving signal are disadvantageously superimposed on the detection signal transmitted in the second detecting wiring pattern 34b. This results in inaccurate determination of the angular velocity. In order to avoid this problem, in the configuration son r FIG. 7, the compensation wiring pattern 35 to be electrically connected to the second detecting wiring pattern 34b is disposed adjacent to the first driving wiring pattern 33a. In this case, the compensation wiring pattern 35 is disposed so that capacitance Ch between the first driving wiring pattern 33a and the compensation wiring pattern 35 becomes substantially equal to the capacitance C3 between the second driving wiring pattern 33b and the second detecting wiring pattern 34b. 
With this arrangement, signal components caused by the first driving signal transmitted in the first driving wiring pattern 33a are generated in the compensation wiring pattern 35, and cancel the noise components caused by the second driving signal transmitted in the second detecting wiring pattern 34b. 
Thus, the noise components caused by the driving signals can be eliminated from the detection signals transmitted in the detecting wiring patterns 34a and 34b. As a result, the correct angular velocity can be obtained on the basis of such detection signals.
There is a demand for a reduction in the size of the vibrating gyroscope 1. However, in the configuration shown in FIG. 7, the vibrating sensor device 31 and the signal processing circuit 32 must be disposed in the same plane of the substrate 30. Accordingly, a large space is required for the substrate 30, and thus it is difficult to reduce the size of the substrate 30. As a consequence, the overall size of the vibrating gyroscope 1 cannot be reduced.
Additionally, in the configuration shown in FIG. 7, the compensation wiring pattern 35 is provided to compensate for noise components contained in the detection signal transmitted in the second detecting wiring pattern 34b. It is thus necessary to reserve space for the compensation wiring pattern 35. This hampers efforts to reduce the size of the substrate 30, making it difficult to miniaturize the overall vibrating gyroscope 1.
Accordingly, in order to solve the above-described problems, it is an object of the present invention to provide a compact vibrating gyroscope without impairing the accuracy in determining the angular velocity.
In order to achieve the above object, according to the present invention, there is provided a vibrating gyroscope including a vibrating sensor device provided with a vibrator. A signal processing circuit is connected to the vibrating sensor device, and generates a driving signal for driving the vibrator and supplying the driving signal to the vibrating sensor device, and processes a detection signal generated on the basis of a vibration of the vibrator caused by a Coriolis force. The vibrating sensor device is disposed on one of an obverse surface and a reverse surface of a substrate, and the signal processing circuit is disposed on the other surface of the substrate. The vibrating sensor device and the signal processing circuit are connected via a through-hole.
With this arrangement, the substrate can be considerably reduced compared to a conventional vibrating gyroscope in which the vibrating sensor device and the signal processing circuit are disposed in the same plane of the substrate.
In the aforementioned vibrating gyroscope, the signal processing circuit may be an IC device. With this arrangement, the vibrating gyroscope can further be miniaturized. The manufacturing process of assembling the vibrating gyroscope can also be simplified.
The vibrating sensor device and the signal processing circuit may face each other with the substrate therebetween. The center position of the vibrating sensor device may substantially coincide with the center position of the signal processing circuit.
With this configuration, the vibrating gyroscope can be considerably reduced compared to a conventional vibrating gyroscope in which the vibrating sensor device and the signal processing circuit are disposed far away from each other.
In the aforementioned vibrating gyroscope, a first detecting wiring pattern and a second detecting wiring pattern, which form a pair, may extend in opposite directions from the vibrating sensor device on the substrate. A first driving wiring pattern and a second driving wiring pattern for respectively allowing a first driving signal and a second driving signal, which are 180 degrees out of phase with each other, to pass therethrough may extend from the vibrating sensor device on the substrate. The first and second detecting wiring patterns and the first and second driving wiring patterns may be disposed so that a value obtained by multiplying a capacitance between the first detecting wiring pattern and the first driving wiring pattern with a capacitance between the second detecting wiring pattern and the second driving wiring pattern becomes substantially equal to a value obtained by multiplying a capacitance between the first detecting wiring pattern and the second driving wiring pattern with a capacitance between the second detecting wiring pattern and the first driving wiring pattern.
It is thus possible to eliminate the need for a wiring pattern to compensate for noise separately from the regular wiring patterns. The size of the vibrating gyroscope can further be reduced.
The first and second driving wiring patterns may extend from the vibrating sensor device in opposite directions along a line passing through the center of the vibrating sensor device. The first and second detecting wiring patterns may be disposed substantially orthogonal to an extending direction of the first and second driving wiring patterns along a line passing through the center of the vibrating sensor device.
A capacitance between the first detecting wiring pattern and the first driving wiring pattern, a capacitance between the second detecting wiring pattern and the second driving wiring pattern, a capacitance between the first detecting wiring pattern and the second driving wiring pattern, and a capacitance between the second detecting wiring pattern and the first driving wiring pattern may be substantially equal to each other.
With this arrangement, noise components caused by the driving signals contained in the detection signals can be removed with higher precision.